Arduino mega驱动UHF RFID读取RSSI值

sky5932734 2011-10-17 17:26 楼主

Arduino mega驱动UHF RFID读取RSSI值
RSSI（Received Signal Strength Indicator）是接收信号的强度指示，它的实现是在反向通道基带接收滤波器之后进行的。RSSI技术是通过接收到的信号强弱测定信号点与接收点的距离，进而根据相应数据进行定位计算的一种定位技术。现在通过代码得到RSSI值。

硬件：
   1、soliddigi Uart TTL UHF RFID module
   2、902~928MHz 5dBi RFID Antenna
   3、soliddigi Arduino mega

读取RSSI使用Uart RFID控制指令集中的Command Inventory with RSSI指令，

Arduino代码如下：

//RFID reads the tag by Arduino mega
unsigned int status = 0;
unsigned char val,RSSI,Tag_num,I,Q;
unsigned char SCMD[] = {0x43,0x03,0x01};
unsigned char Rcard[12];
unsigned char Freq[3];
void setup()
{
Serial.begin(115200);
Serial1.begin(115200);
}
void loop()
{
if (status == 0)
Serial1.write(SCMD,3);
delay(500);
if (Serial1.available() > 0) {
val = Serial1.read();
switch(status) {
case 0: // parse 0x44
if (val == 0x44)
{status = 1; /*Serial.print(val);*/}
break;
case 1: //parse 0x16
if (val == 0x16)
{status = 2; /*Serial.print(val);*/}
else if (val == 0x05)
{Serial.println("No Tag read");
status = 22; /*Serial.print(val);*/}
break;
case 2:
if (val > 0)
{status = 3; Tag_num = val;
Serial.print("Tag_num = ");
Serial.println(Tag_num,HEX);}
break;
case 3:
RSSI = val; I = (val&0x0F)*2; Q = (val>>4)*2;
Serial.print("RSSI = ");
Serial.println(RSSI,HEX);
status = 4;
break;
case 4:
case 5:
case 6:
Freq[status - 4] = val;
status ++;
// Serial.print(val);
break;
case 7:
if (val == 0x0E)
{status = 8; /*Serial.print(val);*/}
break;
case 8:
if (val == 0x30)
{status = 9; /*Serial.print(val);*/}
break;
case 9:
if (val == 0x00)
{status = 10;/* Serial.print(val);*/}
break;
case 10:
case 11:
case 12:
case 13:
case 14:
case 15:
case 16:
case 17:
case 18:
case 19:
case 20:
case 21:
Rcard[status - 10] = val;
status ++;
// Serial.print(val);
if (status == 22) status = 0;
break;
case 22:
if (val == 0x00) {status = 23; /*Serial.print(val);*/}
break;
case 23:
if (val == 0x00) {status = 24; /*Serial.print(val);*/}
break;
case 24:
if (val == 0x00) {status = 0; /*Serial.print(val);*/}
break;
default:
break;
}
}
}

复制代码

RSSI值赋给一个变量，从Arduino的serial port可见：

更多操作指令，请参考 Uart RFID 控制指令集：
TTL UART/USB Long Range UHF RFID reader Module (ISO18000-6C EPC G2) UART Protocol

http://www.soliddigi.com/download/showdownload.php?id=54&lang=en